What’s the most interesting thing you learned from a book recently? At least according to Herodotus, the Persian emperor Xerxes I was marching his army through a forest when he came across a sycamore tree so beautiful “that he was moved to decorate it with golden ornaments and to leave behind one of his soldiers to guard it.” This will not surprise anyone who has ever seen a great sycamore tree, of course, but still. (I learned this from Annie Dillard’s “Pilgrim at Tinker Creek.”)